The use of microwaves to thaw mammalian solid organs viably preserved in the frozen state continues to intrigue and promise. The objective of measuring the thaw rate by utilizing the electrical properties of frozen tissue has been accomplished in the past year by computerizing the resonant frequency shift in a newly designed chamber. This system is based on the two master's theses in engineering and three papers. It has become apparent that small changes in geometry and volume cause large changes in frequency shifts. Therefore, at the present time, each organ must be made to serve as its own control. This is necessitating modifying the chamber to record the freezing curve. This work is in progress. Then the objective of applying microwaves evenly to solid organs by measuring the heating potential distribution should be able to be accomplished simply. The frequency shift during the freezing curve will be reversed by computer during the thawing curve. This equipment has and will be tested on simulated biologic specimens, minced kidneys, simulated organs, and finally living canine kidneys.